Sewage and more sewage

Several questions have come in about sewage.

I like that.  We all excrete and the more of us who think about what to do with it the better, I hope, for our Earth’s water, soil and energy.

Here’s one:

“Hello Michael ,

A  very good book ………. a lot of information and I will try to do
what you have done
Yesterday  I  went  to  a home show …. they had a sewerage treatment
system but it was only good enough for watering the garden.
He could not make it good enough to be like yours
I wonder if a water filter & UV lamp like yours is all that is needed to be added
to make things work
Do you have any brief comments to point me into the right direction

Best regards,


Mr I, the answer is, “yes’.

Add a water filter and a UV and you’re away; safe water with a system easily serviced by you or a local plumber.  The best filter is about a meter of sand; roughly equal in its capacity to kill viruses and pathogens when combined with UV to a several hundred thousand dollar reverse osmosis filter. Options for the sand filter include the one used for irrigation shown in my book, Sustainable House, or a 1500 litre to 3000 litre tank filled with sand will do the trick.

Ensure you keep the water flow to the UV about half the rate of its design capacity so it’s sterilizing efficiency is kept at its highest. So, for example, if the UV will handle a flow rate of 20 litres a minute keep the water flow down to 10 litres a minute.  If you’re using the water to irrigate, to flush your toilet or to wash your clothes that’s plenty.

May the reused water be with you, Mr I,


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  • Michael Mobbs

    Michael is a former Environmental Lawyer who is uniquely placed to consult in four main areas:

    • Sustainability Coach and Speaker,
    • Sustainable Urban Farm Design greening, watering and cooling the cityscape, roads, parks, suburbs,
    • Major Projects Consultant Commercial and Industrial,
    • Residential Sustainability Consultant.
    For permission to re-print any articles or to book Michael for a speaking engagement go to Contacts. Please ensure all quotes from Michael's blog include a reference to